The success of thalidomide in treating various medical conditions and preliminary evidence of the drug's antiviral properties have created intense interest in thalidomide in the treatment of HIV disease. Since the pharmacokinetic profile of thalidomide has not been determined, we propose to study patients enrolled in thalidomide protocols currently active at the Rockefeller University to ascertain the pharmacokinetic properties of the drug. An additional source of patients for this study is Memorial Sloan Kettering Cancer Center (MSKCC), which is the site for ACTG Protocol 267, designed to gather more information on the safety, tolerability, antiviral activity, and immunological effects of thalidomide to determine if intensive long-term investigation of the drug as an antiviral agent is warranted. Pharmacokinetic analysis for three doses of thalidomide at 3 times during the study is an integral aspect of this investigation. We propose to execute those pharmacokinetic studies at the Rockefeller University Hospital in a collaborative arrangement with Dr. Susan Krown at MSKCC to facilitate ACTG 267 as well as to enhance our understanding of thalidomide in our on-going studies of the drug.